Distinct phenotypes require distinct respiratory management strategies in severe COVID-19

Abstract

Coronavirus disease 2019 (COVID-19) can cause severe respiratory failure requiring mechanical ventilation. The abnormalities observed on chest computed tomography (CT) and the clinical presentation of COVID-19 patients are not always like those of typical acute respiratory distress syndrome (ARDS) and can change over time. This manuscript aimed to provide brief guidance for respiratory management of COVID-19 patients before, during, and after mechanical ventilation, based on the recent literature and on our direct experience with this population. We identify that chest CT patterns in COVID-19 may be divided into three main phenotypes: 1) multiple, focal, possibly overperfused ground-glass opacities; 2) inhomogeneously distributed atelectasis; and 3) a patchy, ARDS-like pattern. Each phenotype can benefit from different treatments and ventilator settings. Also, peripheral macro- and microemboli are common, and attention should be paid to the risk of pulmonary embolism. We suggest use of personalized mechanical ventilation strategies based on respiratory mechanics and chest CT patterns. Further research is warranted to confirm our hypothesis.

Keywords: COVID-19; Mechanical ventilation; Non-Invasive ventilation; Positive end expiratory pressure; Prone position; SARS-CoV-2.

Fig. 1

Summary of the key points for respiratory management of COVID-19 patients according to the three distinct phenotypes. Phenotype 1: good compliance, but severe hypoxemia. PEEP should be set with the aim to redistribute pulmonary flow and reduce shunting. In this case, using the principles generally applied in ARDS, and thus setting the PEEP according to the best driving pressure, will probably lead to use of lower PEEP (as the compliance is good), resulting in less oxygenation. iNO could be considered in these cases, and prone positioning can redistribute perfusion, but is generally not very useful at this stage. Phenotype 2: atelectasis and derecruitment are predominant. In this case, high PEEP and prone positioning can recruit non-aerated areas of the lung. Recruitment maneuvers (RMs) may play a role in these cases, whereas iNO is less useful. Phenotype 3: typical CT pattern of moderate-to-severe ARDS, with alveolar edema and low compliance. Respiratory settings should follow the general principles applied for ARDS. PEEP should be set according to the best driving pressure; eventually, RMs, prone positioning, and ECMO may be considered.

Fig. 2

Key points summarizing our recommendations for the respiratory management of COVID-19 patients.

Fig. 3

Genoa algorithm for the advanced respiratory management of patients with COVID-19-related respiratory failure. This algorithm establishes objective tests which can be performed at bedside to determine whether a patient can be managed on oxygen alone, thus rationalizing ventilator and PPE use, and provides clear steps for escalation to CPAP and intubation.

Fig. 4

Individualized strategies and pathophysiological features according to chest CT findings.

Fig. 5

Genoa algorithm for the weaning and extubation of patients with COVID-19.